I've visited the website and I'm confused: are Facebook-less creatures unable to partake in the service? Wouldn't that be kind of weird?
Right now we require Facebook, because we heavily rely on the graph to match groups while requiring minimal work from our members. For instance, we want to make sure the two groups don't already know each other, and we haven't figured out a good way to replicate this functionality without Facebook (e.g. "tell us all the people you know!")
If you have any ideas, though, we'd love to hear them.